Step 1: Set Your Build Volume
Enter the Build Volume X and Y in millimetres. The packer ignores Z — it packs by footprint only, on the assumption that anything fitting horizontally also fits vertically (true for almost every consumer FDM machine).
- Bambu A1 / X1C / P1S — 256 × 256
- Prusa MK4 / MK3S+ — 250 × 210
- Ender 3 / Neo — 235 × 235
- Voron 2.4 350 — 350 × 350
- A1 Mini — 180 × 180
Step 2: Drop In Your STLs
Drag every part you want to print into the upload zone. The tool computes each model's axis-aligned bounding box on the XY plane and lists every file with its footprint dimensions and the auto-detected triangle count.
The packer treats each STL as a rectangle equal to its bounding box. That is conservative — oddly-shaped parts could nest tighter — but it is fast and never produces overlaps.
Step 3: Spacing and Rotation
- Part Spacing defaults to 3 mm. Bump it to 5 mm if your skirts or brims are wide. Drop it to 1 mm if you are running brimless on a clean PEI sheet.
- Allow 90° Rotation almost always improves utilisation by 10–20%. Leave it on unless your parts are layer-direction-sensitive (carbon-fill, hinges, joints loaded in tension along a known axis).
Step 4: Pack the Plates
Hit Pack plates. The bottom-left algorithm fills the first plate top-down and left-to-right, opens a second plate when the first is full, and keeps going until every part has a home. The summary shows:
- The total plate count — the number of separate prints you have to start.
- The average utilisation per plate, as a percentage of the build volume.
- A 2D preview of every plate with each part labelled.
Pro Tip — Aim for 60–70% Utilisation
Below 50% means parts are awkwardly sized for your bed; consider rotating individual parts manually before packing, or splitting the longest parts in Slicer Pro. Above 75% the parts are crammed and a single brim or warped corner can kill the entire plate.
Why Not Slice Them All Together?
You can — PrusaSlicer's auto-arrange does similar packing — but the Packer runs before you commit to a slicer profile. That means you can compare plate counts across different printers without setting up a profile for each machine.
Useful when deciding whether to send a job to your A1 Mini (cheap, 180 mm bed, more plates) or the enclosed X1C (faster, 256 mm bed, fewer plates). The Packer answers that in a few seconds.
Pairs Well With…
- Run a giant model through Slicer Pro first. Drop the resulting segment STLs into the Packer to fit all thirty fragments across the minimum number of plates.
- Use the Mega Estimator on the packed plates to project total filament cost and print time before pressing Print.
- Pair with Orientation Optimizer to settle each part on its lowest-area orientation before packing — smaller footprints mean more parts per plate.